1. Field of the Invention
This invention relates to the manufacture of molded concrete products, and more particularly concerns a mold for producing block structures of varied design.
2. Description of the Prior Art
Specialized concrete blocks find widespread use in constructions that provide unique appearances while fulfilling functional requirements. For example “paver blocks” are generally employed by emplacement upon substantially flat ground surfaces in abutting relationship to produce walkways, patio areas, or decorative flooring. Such paver blocks are generally configured as monolithic molded pieces having substantially flat upper and lower faces in parallel juxtaposition spaced apart by about 2 to 4 inches, and bordered by a perimeter sidewall that extends orthogonally between said upper and lower faces.
In conventional paver blocks, the perimeter sidewall is of rectangular shape. This invention is concerned with paver blocks and related concrete blocks having sidewalls of non-rectangular contoured shapes adapted to interact with contiguous blocks in tight fitting abutment to produce an aesthetically pleasing and functionally sound flat assemblage. Such blocks of customized shapes are further useful in filling floor or wall areas having irregular boundaries such as triangular or other polygonal shapes.
The production of blocks molded from concrete is well known. In a typical block-molding operation, pourable concrete is entered by downward gravity flow into an underlying mold structure of generally elongated, flat contour having a multitude of identical cavities with open upper extremities. When filled with concrete to the height of the upper extremity of each cavity, the lower, generally flat bottom of the cavity produces the lower surface of the resultant block, and the upper surface of the concrete becomes the upper face of the block. Immediately after the concrete is poured into the cavities, the mold is vibrated so as to deaerate the still fluid concrete and cause the upper surface in each cavity to be level and smoothly formed.
The mold, generally positioned upon a pallet, is then removed and allowed to stand motionless until the concrete sets to a hardened structure. The resultant blocks are extricated from the mold, and the mold, generally of strong metal construction, is repeatedly used again. Examples of such traditional block-making processes are disclosed in U.S. Pat. Nos. 5,219,591; 5,686,009; 6,007,321; 4,218,206; 5,395,228; and 4,111,627.
U.S. Pat. No. 4,389,036 discloses the manufacture of concrete blocks having hollow interiors. Such blocks are made by providing conically shaped inserts centrally positioned within the mold cavities. Upon solidification of the concrete, the inserts, which may be of plastic construction, are removed.
In the molding of metal objects by the “lost foam” process, pieces of foamed polymer such as polystyrene are shaped to have the exact configuration of the intended molded object. The shaping of the polymer foam may be done by automatic CNC cutting machines. The shaped structure is then embedded within a bed of foundry sand. When molten metal is poured into the cavity occupied by the shaped foam, the foam is vaporized. Upon cooling and solidification and removal of the enveloping sand, a molded object is obtained which has the exact shape as the precursor shaped polystyrene foam.
The aforesaid techniques are not amenable to the short run production of shaped concrete articles, particularly where a mold is used just once for the production of custom designed blocks of varied and unusual configurations.
It is accordingly an object of the present invention to provide a process for the production of concrete blocks of varied configuration.
It is another object of this invention to provide a mold assembly suitable for use in the aforesaid process.
It is a further object of the present invention to provide a process for the fabrication of accurate and varied low cost molds for the production of concrete paver blocks.
These objects and other objects and advantages of the invention will be apparent from the following description.